Cardiac surgical procedures have become very common worldwide. By some estimates, 700,000 are performed annually in the USA. Despite their complexities, the risk associated with these procedures has steadily declined over the years. However, the temporary pacing wires that are placed on essentially every heart at the completion of the procedure have not improved their safety profile in close to two decades. As a matter of fact, surgeons continue to use temporary pacing wires that were designed in 1992. These temporary pacing wires/leads, when removed several days post-operatively, continue to pose a significant risk of bleeding to the patient. Such bleeding could lead, in about 1% of cases, to tamponade and even death. These devices are so hazardous that some surgeons prefer to refrain from using them rather than expose the patient to the bleeding risks.
Several different prior art pacing wires will now be discussed for background purposes. In various prior art pacing wires, a distal end of the pacing wire is secured to the heart with a suture. A few days later, the pacing wire is removed by pulling on the proximal end of the wire, which is outside the patient's chest, in essence tearing the tissue attached to the distal end and pulling it through the chest wall. The major complication of such a system is the potential bleeding complications that may ensue by ripping a portion of the heart tissue in order to dislodge the sutured distal end of the device. Another minor, yet annoying, feature of this prior art pacing wire is encountered if the surgeon decides to lift the heart and inspect it after securing the pacing wire in place. In such cases, he or she will often dislodge/rip the distal end of the pacing wire off of the patient's heart, and must then reattach the device to the heart. This may lead to intraoperative bleeding that can make the surgery more difficult to complete. Another shortcoming of this device is that, when securing the distal electrode to the heart with a suture, bleeding may occur from the suture itself as the suture passes into the heart tissue. In such cases, additional sutures may be required to stop the bleeding.
In other prior art pacing wires, the pacing wire's distal pacing electrode is driven into, rather than sutured to, the heart tissue. In such pacing wires, the distal electrode is attached to a helical suture that has a curved needle at one end. The curved needle is driven into the heart and pulled through until the distal electrode is embedded within the heart tissue. The curved needle and a portion of the helical suture are then cut leaving the distal electrode positioned inside the heart tissue. A few days later, the pacing wire is removed, by pulling on the proximal end of the wire/lead that is outside the patient's chest. In this case, instead of tearing the tissue that is attached to the distal end of the pacing wire, and pulling the distal electrode through the chest wall, the distal electrode slips out of the myocardium/tissue of the heart and is removed. Unfortunately, however, bleeding can still occur from the tract evacuated by the electrode and attached wire with all of the associated morbid consequences including death. Furthermore, this arrangement is also subject to all of the other shortcomings that plague the prior art arrangement discussed above in terms of dislodgement and bleeding associated with resecuring the electrode to the heart.
Yet another prior art pacing wire arrangement calls for securing a permanent clip to the heart that has an antenna (in the form of two parallel rabbit ears), or a round receptacle through which a pacing wire may be introduced. The problems with this design are multifold. First, since the electrode and pacing wire are loosely attached together, the potential for the wire to dislodge from the electrode antenna in such a way as to stop pacing is very high as a result of: (1) the beating of the patient's heart; (2) the patient's movements; or (3) the patient's respiratory fluctuations. Also, the permanent electrode is disadvantageously left on the heart permanently. In addition, securing the electrode to the heart poses the risk of causing bleeding as described above in regard to the arrangements of FIGS. 1 and 2. Lastly, disengaging the wire from the permanent electrode could potentially be hazardous.
In brief, currently known cardiac pacing wires continue to present significant hazards to patients. Accordingly, there is a need for improved, safer cardiac pacing wires.